Nano-emitters such as single molecules are several orders of magnitude smaller than the wavelength of visible light. Therefore, the selection of single nano-emitters and the control of light-molecule interaction processes, including fluorescence efficiency, can be desirable for certain applications. To this end, one approach is to use optical nano-antennas to enhance electric fields and thus improve emission, but achieving reliable fluorescence enhancements is still an ongoing challenge.
Efforts to address this challenge have included use of antenna-like structures, sometimes referred to as optical antennas. While antennas are more commonly appreciated as the transmitting/receiving (or transceiving) conductive structures at the end-point components in radio communication and broadcasting systems, aspects of the present disclosure are directed to optical antennas which are configured to produce significant and/or optimal enhancements to the electric field when illuminated at resonant wavelengths. By using precise nanofabrication technology such as electron- and ion-beam lithography, these optical antennas can be manufactured to operate in the visible region of the spectrum.